KRISTEN ZELLAR, IWU STUDENT: Young college students, they need to -- they need to be aware.

BALDWIN: Kristen Zellar was a junior at IWU when Tricia disappeared.

ZELLAR: We were advised to stay in our dorms if you were a girl.

BALDWIN: But a week after Tricia's disappearance, Kristen and her roommate Heather needed to go to the Marsh Grocery Store.

(On camera): You thought you'd be safe, you thought you'd be fine?

ZELLAR: Yes.

BALDWIN: Couple of blocks away. ZELLAR: Exactly. It's not far at all. I can see the campus from Marsh so, you know, what's going to happen?

BALDWIN (voice-over): It was getting dark by the time they left the shopping center walking the same route Tricia would likely have taken.

ZELLAR: We were maybe halfway up the road when Heather turned to me and said, did you -- did you happen to notice that brown van? And I said, no.

BALDWIN: Then the van passed again, slowly.

ZELLAR: We still weren't alarmed. He came by again.

BALDWIN (on camera): A third time?

ZELLAR: A third time, yes. Really slow this time. Looking at us. The hair on the back of our necks started to stand up.

BALDWIN (voice-over): The van pulled up right up be side them.

(On camera): How close, show me.

ZELLAR: He was, I mean, his wheels were right on the side of the curb. And this was me. This was Heather and he leaned over, started to say something, and at that point we're both like, run, just run.

BALDWIN (voice-over): The girls called security, describing a two-tone van driven by a man with mutton chopped side burns. Officers spotted the van and questioned the driver, a man named Larry Hall. Hall said he'd been looking for a friend's address but the address he gave didn't exist. So officers let Hall go.

GARY MILLER, INVESTIGATOR: We all knew that we had something really bad here. We had an abduction.

BALDWIN: Jessica's badly decomposed body was found in an Indiana cornfield weeks later. But then, like Tricia's, Jessica's case went cold.

MILLER: There's a lot of times you wonder whether you'll ever solve it but you know that you're going to keep going, you're going to check everything out, you're going to recheck everything.

BALDWIN: For over a year, Miller scoured local police reports and then, a break. A vehicle reported in a county nearby. The owner? Larry Hall.

MILLER: He had been involved in stopping some girls. Those girls were scared. They ran from him. BALDWIN: In the last six months, Hall's van was spotted by more than 11 girls in five different towns close by. Including those where Jessica lived and where her body was found. Now, Miller contacted the police in Hall's hometown to arrange for an interview.

MILLER: He initially said, no. You know, he hadn't been over here.

BALDWIN: Miller had to coax Hall to admit being near Jessica's house.

MILLER: I said, well, would you remember, you know, if you stopped and offered girls a ride or asked them to get in your van? He's like, he stops and talks to everybody.

BALDWIN: After a few questions, Miller took a gamble and put a photo of Jessica down in front of Hall.

MILLER: He immediately flinched. He turned to his right and he put his hand up over his face like he didn't want to see the picture. He told me he didn't think he'd ever seen that girl.

BALDWIN: Later, a heartbreaking mystery --

D. REITLER: There's so little that we can do to find her. I just want to bring her home.

BALDWIN: And a dangerous plan to solve it.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

BALDWIN (voice-over): Larry Hall and his brother, Gary, had always been a little different.

(On camera): Look at you two little boys. Which one are you? And which one is Larry?

GARY HALL, BROTHER OF LARRY HALL: This would be me.

BALDWIN: Gary and Larry.

G. HALL: Yes.

BALDWIN (voice-over): In a rare recorded interview obtained by CNN, Larry Hall recounts a tough start.

LARRY HALL, CONVICTED KIDNAPPER: I know when I was born my mother told me that I was blue. That I hadn't got enough oxygen to me or something.

BALDWIN: Identical twin sons growing up hard. In the Hall home there was little money and lots of problems. Author Hillel Levin interviewed Larry Hall.

HILLEL LEVIN, AUTHOR: It was a very cluttered household. They're raised with dysfunction.

BALDWIN: Neighbors say their mother was domineering. Their father drank and sometimes turned violent. He worked at the local cemetery.

(On camera): What was it like growing up next to a cemetery? Was it creepy?

G. HALL: No, not at all, not for me. You know, at 12 years of age, Larry and I started working at the cemetery.

BALDWIN (voice-over): As he grew older, Larry had problems fitting in at school.

G. HALL: He was always the backward twin. I was the more dominant outgoing twin. He hung out with what my wife and I and a lot of fellow classmates, called "The Misfits" or the "Stinky" crowd.

BALDWIN: Still, the boys were best friends and as young men Gary and Larry developed a unusual new hobby as civil war re-enactors.

L. HALL: I met a lot of new friends during that time period. And I was able to travel around and meet him at the battlefields and go on tours and stuff. It was a lot of fun.

BALDWIN: Larry was hooked, even growing mutton chops from his hairline to his jowl. Though the re-enactments helped Larry make friends he still struggled with women.

(On camera): What was he like around young women growing up?

G. HALL: Very awkward, quiet, backward.

BALDWIN: Did he ever talk to you about these urges he reportedly says he had urges about women?

G. HALL: Oh, my, gosh. It was absolutely -- it was out of bounds. I had no idea --

BALDWIN (voice-over): Jimmy Keene grew up 135 miles away in Kankakee, Illinois. He didn't know Larry Hall and he had no idea that their worlds would some day collide.

UNIDENTIFIED MALE: Getting third down and five at the 25 yard line.

BALDWIN: For Jimmy Keene, life couldn't have been more different. While Hall was an awkward outsider, Jimmy Keene was a star. Especially under the lights on Friday nights.

KEENE: We would come out here. The lights would be on. The whole stadium would be just completely full and the crowd would be roaring and it was just a very euphoric, unbelievable high. The Friday night games were the biggest rush I've ever had in my life.

BALDWIN: A gifted athlete, he lettered in two sports, studied martial arts and inspired fear in everyone he faced.

(On camera): You like having people terrified of you just a little bit?

KEENE: In that kind of sport, sure, you have to. That's why they called me the assassin.

BLITZER: You were the assassin.

KEENE: Yes, my nickname was the assassin. And the reason my name was the assassin is because I put somebody out in every game I've ever played.

BALDWIN (voice-over): Keene wasn't just the hometown hero, he was his father's namesake.

KEENE: My dad generally sat up in the corner over here. If I made a spectacular play he would give me the, you did good, son, you know.

BALDWIN (on camera): How often was he sitting in the stands?

KEENE: Every single game of my life. He never ever missed a game. He never even missed my practices.

BALDWIN: Did that mean a lot to you?

KEENE: Absolutely. My dad was -- he was my backbone.

BALDWIN (voice-over): Keene was as popular as he was athletic.

(On camera): You're a legend?

KEENE: Yes, I mean, there was no doubt. I mean, they had posters of me all over town. I mean everybody knew who I was with my sports ability. So, yes, I was the most popular guy around. There's no question, I was voted most popular guy in school.

BALDWIN (voice-over): Jimmy seemed to have everything. Except enough money to keep up with the rich kids at school. And he only saw one way to get it. He started selling drugs and quickly learned he was good at it.

KEENE: You're making decent money you don't think, is this a wrong thing that you're doing. So I kept growing into it and growing into it and by the time I was 20 years old I mean, I was sitting on top of an empire.

BALDWIN: By Keene's own account, he was pulling in around $1 million a year. He was addicted. Not to the drugs, but the money.

KEENE: It's hard to walk away from that kind of money, especially a 20-year-old. BALDWIN: So he didn't. And that single decision would change the rest of Jimmy Keene's life. And bring him face-to-face with an alleged serial killer.

(COMMERCIAL BREAK)

BALDWIN (on camera): License plate, Extra HP.

KEENE: Extra HP.

BALDWIN (voice-over): By the early '90s, Jimmy Keene was on top of the world. His booming business afforded him a lavish lifestyle with large homes, souped up Corvettes and an endless supply of women.

KEENE: I would have 30 or 40 keg parties with volleyball nets, live bands. We'd have literally a thousand people or more sometimes. I mean these were gigantic, huge parties.

BALDWIN (on camera): You were the guy women wanted to be with and guys wanted to be best friends with.

KEENE: This was a hidden trap door that you could open and when you would open it, you have another hidden closet back in here. You can see my old safe is still here. And this was pretty much just my Ft. Knox room.

BALDWIN: For 15 years, Keene's empire remained hidden and growing. But as he lived the high life, his father fell on hard times, nearing the brink of financial ruin.

KEENE: My dad, to me, was superman. And to see him in such a hurt way really killed me.

BALDWIN: So Jimmy used his drug fortune to bail his father out. Then continued to support him.

KEENE: Even though it was coming from something wrong I felt I did something very right to make his world right.

BALDWIN: But the money never seemed to be enough. And Keene couldn't stop watching his back. By the fall of 1996, the pressure of life in the fast lane was catching up. KEENE: I had woke up in the middle of the night and I was laying there wide awake and I said, you know, I am tired of running like this. I said, I really just want this all to end.

BALDWIN: And it was all about to end but not the way Keene had planned. Just two weeks later --

KEENE: I heard the front door rattle and I thought it was just the wind. It was in November. And next thing you know, boom, the whole door just blew off the hinges and then they came flying in in a straight file line with their guns drawn and their black uniforms. We'll blow your head off, we'll do this, just move once --

BALDWIN: For Jimmy Keene it was over.

KEENE: Everything stops and goes in slow motion. You don't even feel like it's real.

BALDWIN: He was ultimately dragged to jail. He pleaded guilty hoping to minimize his sentence. And at first, the federal prosecutor Larry Beaumont was willing to negotiate.

BEAUMONT: Initially we tried to what we call "flip" him to see if he would give us other drug dealers at the time. And I think he refused so our reaction was to make sure he gets the maximum penalty.

BALDWIN: Beaumont got his way and Keene got 10 years. It knocked the life out of him and broke his father's heart.

KEENE: Any hopes and dreams he had had for me at that point in life, were gone. He was crushed. I mean, he's very crushed.

BALDWIN: Jimmy Keene could not imagine a way out. Nor guess that a man he'd never met might some day provide him one.

November 1994, Wabash, Indiana. It had been two weeks since Larry Hall recoiled from a photo of Jessica Roach. And investigator Gary Miller had a gut instinct.

MILLER: I really think we're on to something here. This guy portrays this weak, timid person, but, you know, I don't think he truly is.

BALDWIN: Miller thought Hall was vicious and as the investigation unfolded, Miller also thought he knew how Hall abducted Jessica Roach.

MILLER: When he first seen her, she was riding from toward the house going down this way.

BALDWIN: Hall followed and stopped to talk. Jessica got scared and backed away.

MILLER: That's when he opens the door, grabs her, there's a physical confrontation where he overpowers her. Put her in his van and left, probably going up this road right past her house. BALDWIN: In an interview in the Wabash Police Station, Hall surprised investigators by explaining what happened next. "I tied her up but I can't remember with what. I took her pants off."

Hall said he raped her and led her off through the woods. "I laid her up against a tree and put a belt around her neck and she stopped breathing."

Hall said he strangled Jessica from behind so he didn't have to see her face as she died. And that wasn't all.

"All of the girls looked alike," Hall said. "I cannot remember all of them. I picked up several girls in other areas but I can't remember which ones I hurt."

"Several girls in other areas." There were more victims than just Jessica Roach.

Hall said he'd also been near the campus of Indiana Wesleyan University where Tricia Reitler had disappeared.

"I was over there because I needed to be with somebody. There was a small shopping center. I had a van."

Hall said he raped and strangled a girl here, too. Then he identified his victim by pointing to Tricia's picture.

Tricia's disappearance had remained a mystery for 18 months.

G. REITLER: We were just kind of sitting on the sidelines waiting for information to come in.

BALDWIN: With little evidence and local police insisting on another suspect, Tricia's parents, Garry and Donna still suffered.

D. REITLER: I know with each thing that came in the urgency was great. And the heartache was great, too. And the anticipation and the hope.

BALDWIN: Hall's confession met the Reitler's might at least find their daughter. And that Gary Miller had found the killer of Jessica Roach. But the next day, Hall changed his story.

MILLER: As I was talking to him he said, I was just telling you about my dreams. That didn't really happen. He said, it was just my dreams. And I said, Larry, that's not what you said. You said this had happened, you know, you didn't like talking about it because you didn't like the things that you'd done but you never mentioned it being in a dream.

BALDWIN: But he stuck to his new story. Larry Hall was recanting everything.

(END VIDEOTAPE)

(COMMERCIAL BREAK) DON LEMON, CNN ANCHOR: I'm Don Lemon live at the CNN World Headquarters. Here are your headlines this hour. Authorities say the victims in a home explosion in Washington state today are Josh Powell and his two young sons. You remember Powell's wife, Susan Powell Coz, went missing back in 2009. Powell has been the lone person of interest in her disappearance. A foster care case worker dropped the two sons off at the house and said the explosion occurred two minutes later.

Coming up tonight on CNN, we'll have more on that story.

In Syria, the violence is unrelenting. At least 43 people killed today, including five children, most of them in the city of Homs where hundreds have died in recent days. Opposition group called for a two- day civil strike starting today to put pressure on President Bashar al-Assad's government.

Nearly 500 people on two Florida based cruise ships are recovering from a stomach virus. The CDC is trying to find out what caused a noravirus outbreak. The onus spread from person to person through a contaminated food or water or by touching contaminated surfaces.

At least 300 people are dead following a fierce snowstorm battering London and other parts of Europe. The storm forced Heathrow International Airport to cancel about half of its flights.

Make sure you join us at 10:00 p.m. Eastern for more on those stories. In the meantime, "CNN PRESENTS: TO CATCH A SERIAL KILLER" continues now.

(BEGIN VIDEOTAPE)

BALDWIN (voice-over): Larry Hall had confessed to killing Jessica Roach, Tricia Reitler and two other women. And then he took it all back, claiming it was just his imagination.

L. HALL: I did confess to certain policemen that I had dreams that I did things.

BALDWIN: But investigator Gary Miller had other evidence like the witness who drove by this cornfield the night of Jessica's murder.

MILLER: That person testified that he was absolutely sure that when he went by here that night there was a van, there was a guy coming from the corn field to get in his van.

BALDWIN: And a search of Hall's house and van revealed he'd been casing out small college towns and keeping suspicious notes. "Seen joggers and bikers. Many alone. Check colleges, parks. Seen some prospects."

Hall also made lists for the hardware store. "Buy two more plastic tarps. Cover all floor and sides of van." And Hall wrote himself troubling instructions. "No body contact. Buy condoms. Buy two more leather belts. Find one now." Amongst Hall's things, investigators found newspaper clippings about Roach and Reitler, possessions from other missing girls and pornographic pictures Hall had altered.

MILLER: In those pictures, he had drawn what looked like a rope or a belt around the neck of one of -- of the left side of the mouth he had drawn blood.

BALDWIN: Hall insisted it was all just staged, to make a play for attention. To feel important to police.

L. HALL: I put a bunch of stuff in that van that I drove around with because I knew they'd eventually search my van and find them.

BEAUMONT: In the federal system, if you're guilty of a kidnapping and that kidnapping resulted in a death, then under the sentencing guidelines it's a mandatory life term.

BALDWIN: The Jessica Roach case was over. But the disappearance of Tricia Reitler remained unsolved. And her parents, Garry and Donna, could not stop looking.

G. REITLER: We walked the sides of the roads. We walked the riverbeds. You know, we looked under the culverts. You know, we end up going to crack houses because somebody had a lead.

D. REITLER: If you see something on the side of the road, a garbage bag, whatever, it's like -- could that be her?

BEAUMONT: It was such a horrendous crime to lose your daughter and never find out what the heck happened to her.

BALDWIN: Larry Beaumont kept looking, too.

BEAUMONT: I actually made arrangements on a couple of occasions to go out and look for the body.

BALDWIN: Beaumont called in specialized military and law enforcement units to search.

BEAUMONT: We were not able to find it. So rather than give up, it occurred to me that obviously, Larry Hall knew.

BALDWIN: Beaumont needed answers and turned to an unlikely source to get them. He needed someone to befriend Larry Hall. Someone charismatic, someone on the inside.

Larry Beaumont needed Jimmy Keene. Beaumont had sent both Keene and Hall to prison. Now he hatched a risky plan that would bring them together.

Keene was 10 months into his sentence when Beaumont brought him into talk.

KEENE: Scared me. I thought this was some trick.

BALDWIN: Keene watched nervously as Beaumont pushed a folder across the table.

KEENE: And I open it up and the first thing I seen was a picture of a mutilated dead girl. And I flipped the next page and there was a different mutilated dead girl.

BALDWIN: And there was a portrait of Tricia Reitler.

KEENE: At that moment I looked up at Beaumont and he says, Jimmy, we need you to help us with this case.

BALDWIN: Beaumont wanted Keene to go undercover, to transfer from his low security lockup to a dangerous prison. And to befriend alleged serial killer Larry Hall.

KEENE: He says, if you can get solid confessions from him and if you can help us locate the bodies that are still missing, we're willing to completely wash your record.

BALDWIN: Keene's mission? To learn where Tricia Reitler was buried.

BEAUMONT: The purpose of this operation was to find that body.

BALDWIN: Beaumont made it clear, no body, no early release. Keene would have to serve the rest of his 10-year sentence. But Beaumont believed Keene could do it.

BEAUMONT: He's smart. He's articulate. He's not afraid. And I knew he wanted to get out.

BALDWIN: For Keene, it was a chance for redemption. To restore his family name and, says author Hillel Levin, to get his life back on track.

LEVIN: This deal was a way for him to get home and it was also a way for him to do good, the kind of take this bad thing he had done and to somehow turn it inside out, and make it something that would solve a crime.

BALDWIN: But it wouldn't be easy.

(On camera): It's fair to say he was risking his life. He could have been killed.

BEAUMONT: It was dangerous, absolutely.

KEENE: It was highly risky. These people in those types of places haven't got anything better to do but try to hurt you and kill you, too.

BALDWIN (voice-over): Keene was unsure. But a phone call home put his doubts to rest. Keene's stepmother said his father had suffered a stroke.

KEENE: She said, he's in really bad shape. We wish you were here. This is terrible that you're in a spot where you're in right now because we could lose him.

BALDWIN: Keene needed to get home fast to Kankakee fast and there was only one way to make that happen. He had to face an alleged serial killer first.

KEENE: I decided, you know what? However bizarre or how far out or whatever this mission that Beaumont wants me to go on, I'm going to do it.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

BALDWIN (voice-over): Driving up to the prison in Springfield, Missouri, Jimmy Keene didn't know if he'd made the best or worst decision of his life.

KEENE: I started to get cold feet. And I looked at the U.S. Marshal and I said, listen, I said, you know, how do we know Beaumont is going to live up to his word? They all assured me he would. And I said, well, you know, I'm not really sure if I can do this.

BALDWIN: But there was no turning back. And he needed to prepare. Agents had warned him to be careful.

KEENE: We don't want you to approach him for at least six months because he's a very cagey individual. If he senses one thing wrong, he goes into a shell like a turtle and you'll never get him back out once he's in.

BALDWIN: But Keene didn't have time to wait. He needed to get home to his ailing father so hours after becoming a Springfield inmate, he spotted Larry Hall. And made his first move.

KEENE: I made it a point for us to bump shoulders together and as we gently bumped shoulders together, I turned around, said, excuse me, I said, listen, I said, I'm new here, I said, you wouldn't happen to know where the library is, would you?

BALDWIN: Hall offered to show Keene the way.

KEENE: And I just reached over and kind of slapped him on the shoulder and I said, thanks a lot, I appreciate that from a cool guy like you.

BALDWIN: Over the next week, Keene watched Hall's every move from his cell across the hall.

KEENE: And I walked up to him and I says, hey, this is where I'm at, I said, are you in this area here, and he goes, yes, I'm right there. You know, and he bugs his eyes out of his head. I said, well, that's great. I said, you're right by me. I said you know what, I told you you were a cool by and I'm glad that you're by me and all this and that, and that's when he basically offered sometime if I'd ever want to have breakfast with him and his friends.

BALDWIN: Keene was making progress, slowly gaining Hall's trust. But life at Springfield was complicated. And dangerous. So Keene figured out a way to use violence to his advantage. It was a Saturday night and Hall was in the TV room, mesmerized by an episode of "America's Most Wanted" about serial killers. Suddenly another inmate approached the TV.

KEENE: And you could tell this guy had been in for a long time. He was a real big buff guy. And he just walked up to the TV, looked at everybody in there and he decided he's going to turn the TV channel. And he turned it. And I found this very interesting. Larry looked at me and very quietly mumbled under his breath, he goes, hey, I was watching that show.

BALDWIN: Keene leaped into action and knocked the guy out.

KEENE: I nailed him with an upper cut, and then I kicked him through three rows of chairs. He was beat up real bad and had to go to the hospital, and they took me in and threw me in the hole.

BALDWIN: It was worth it. And it was a breakthrough with Hall.

KEENE: He not only now looked at me as a guy that he could look at and say, wow, he thinks I'm cool coming from him, that's a compliment. And now he's also able to protect me.

BALDWIN: Now, Keene had Hall's trust and had him talking. One night, in Hall's cell, he told Keene the truth about what happened to Tricia Reitler.

(On camera): But what Hall told Keene was different from what some investigators believed. It was his story, along with some evidence that created a road map I wanted to follow to try to figure out what happened to Tricia Reitler.

Tricia would have left this supermarket parking lot, walking just a couple of blocks back to campus.

(Voice-over): Somewhere along this road, Hall told Keene he got Tricia into his van. When she fought off his advances, he says he choked her to keep her quiet. Hall told Keene he blacked out and when he woke up, Tricia was naked and lifeless.

Days after her disappearance, investigators found her blood- soaked clothes here, just one block from the supermarket. Hall's own notes indicate what might have happened next. Exactly one week after Tricia's disappearance, Hall wrote, "Cut out stained carpet. Vacuumed van thoroughly. Buy new hacksaw blades. Clean all tools."

(On camera): Along with his notes was this address, 700 West Slocum. We're in the woods, halfway between Marion and Wabash, and it is possible that somewhere out here that Tricia Reitler is buried. KEENE: He says, so he got some lime together, he got a shovel and he got a lantern and then he drove her way out into the woods and he buried her out in the woods.

BALDWIN: He admitted to you --

KEENE: Yes.

BALDWIN: -- that he buried her in the woods?

KEENE: Several times he's admitted that, yes. I basically made him feel like it was OK to tell me his secret.

BALDWIN (voice-over): But Keene still needed the secret that would set him free. The exact location of Tricia's body. Weeks later, he thought he nailed it when he found Hall hovered over a map in the prison workshop.

KEENE: It was a map with red dots over Indiana, Illinois and Wisconsin, and he covered it up really fast.

BALDWIN: Lined up at the edge of the map were a dozen wooden falcons.

KEENE: I said, wow, this is pretty cool, did you make these? He says, yes, I make them. And he goes, it's really cool, isn't it, Jim? He goes, they watch over the dead.

BALDWIN: Falcons, to watch over the dead, and a map marked with dots. It was the information Keene thought would surely lead to the exact location of Tricia's body.

(On camera): In that moment what did you think, this is my ticket to freedom?

KEENE: I did. Because I thought this is it. I've got solid confessions out of him. We know specific details. We know how he's done it now.

BALDWIN (voice-over): Keene believed he had his answer. That he'd soon be free. That he was done forever with Larry Hall. So that night, at lockdown, Keene decided to tell Hall what he really thought.

KEENE: I told him that he was a (EXPLETIVE DELETED) sicko. I told him that he was insane. I said that you are one of the most despicable forms of human life on this planet. He at that point slid away from me, was like really terrified of me all of a sudden, and he says, Beaumont sent you, didn't he? Beaumont sent you, didn't he?

BALDWIN: Keene had blown his cover. And his outburst landed him in solitary confinement.

BEAUMONT: It took some time before we found out that they put Jimmy in the hole so he was not able to communicate with anybody on the outside. BALDWIN: By then, Hall's map and the falcons had disappeared. Worst of all, as Keene was let out of Springfield prison to face Larry Beaumont, he didn't know if what he'd learned was enough to set him free.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

BALDWIN (voice-over): During his months in Springfield, Jimmy Keene got Larry Hall to provide details about several murders Hall was suspected of committing, including Tricia Reitler's. But Keene hadn't met the original requirements of Larry Beaumont's deal.

BEAUMONT: And I told this myself, made it clear to him, that we didn't find the body, no body, no credit.

KEENE: Are they going to be fair and give me what's justifiably right on this? Or are they going to say, here's six months? It was a crapshoot.

BALDWIN: Without a location for Reitler's body, Beaumont had a decision to make.

BEAUMONT: I made arrangements to have him take a polygraph test just to verify what he was telling us was the truth which he passed and he did make a legitimate effort to do what we sent him down there to do.

BALDWIN: So Beaumont urged a federal judge to give Keene credit for time served. Jimmy Keene became a free man and returned home to his aging father.

(On camera): What did you feel like when you were finally released?

KEENE: I was happy as could be. And it was a very bizarre rollercoaster that I went on. It was -- I mean, redemption at its best.

BALDWIN (voice-over): Keene had five more good years to be with his father before big Jim passed away.

KEENE: We both realized once I got out that there is a better world than just always in a constant dash to make money. You know, it was more like, look, let's enjoy each other while we're alive here, you know?

BALDWIN: It was closure for Keene, but not for the families of the alleged victims of Larry Hall. For years, there was no progress and no relief for people like Donna and Garry Reitler. D. REITLER: As a parent, there's the part that you flutter down and that you want to find her and bring her home and you can't. I mean, we've done pretty much physically everything that we can to find her. And there's somebody out there that holds that one answer for us.

BALDWIN: Beaumont, too, felt he'd done all he could and that the pursuit of Larry Hall was over.

BEAUMONT: There wasn't going to be no further prosecution from the federal perspective. He's already serving life imprisonment. He was going to -- you know, he was done.

BALDWIN: Once again, Larry Hall had slipped off the radar. And it easily could have remained that way, except for Jimmy Keene.

First, Keene's story of strange redemption was featured in a "Playboy" article and then a book written by Keene and Hillel Levin.

LEVIN: Once we were able to write about what Jimmy went through, then things happened.

G. HALL: Larry, just like Jimmy Keene calls him, and he is. He's a baby killer.

BALDWIN (on camera): You think your brother is a baby killer.

G. HALL: I don't have no doubt in my mind.

BALDWIN: Do you think your brother killed more than Jessica Roach?

G. HALL: Yes.

BALDWIN: Do you think your brother killed Tricia Reitler?

G. HALL: Yes.

BALDWIN: Rayna Rison? Michelle Dewey?

G. HALL: Yes.

BALDWIN (voice-over): As Gary started talking more openly, detectives approached him asking for help.

G. HALL: I went with the Indianapolis detectives down to try to get my brother to confess. He made me leave the room. He did, in fact, confess on tape to 15 serial murders.

BALDWIN: Larry later retracted, again. And while he can't ever seem to stick to one story, he does, sometimes, seem to have regrets. L. HALL: I didn't want to keep living my life the way I was living it. I wanted things to be different, you know, but I guess I didn't really do the right things and change the way my life was going.

BALDWIN: Larry Hall refused our request for an interview. He has never been charged with crimes against anyone other than Jessica Roach. But Keene's story has caused officials across the country to take another look at Hall.

UNIDENTIFIED MALE: In November of 2010, investigators from the town (INAUDIBLE) Police Department interviewed Mr. Hall at a federal prison in North Carolina.

BALDWIN: In that interview Hall admitted murdering Laurie Depies and provided clues about where to find her body.

UNIDENTIFIED MALE: There's multiple agencies that are looking into him referenced unsolved disappearances.

BALDWIN: Larry Hall may have had more victims than ever imagined.

LEVIN: We understand it's even more extensive than we ever thought. Not 20, but maybe 30 to 40, in terms of the victims.

BALDWIN: That leaves 30 or 40 families still awaiting answers. Which is why, says Levin, it is critical that serial investigations do not stop.

Eighteen years after Tricia Reitler vanished her father, Garry, now believes Larry Hall knows where to find her.

G. REITLER: I think if Larry knew what we go through on a daily basis, you know, wondering where she is, wondering what happened, I don't think he would have any to confess and let us know where she's buried.

BALDWIN: Donna Reitler is not as sure.

D. REITLER: He confessed. He recanted. He confessed, he recanted. Without a body, it's just another possibility.

BALDWIN: More than anything else, they just want their daughter back.

D. REITLER: To have a place to lay her to rest, just to be able to sit and just talk to her.

BALDWIN: As for Jimmy Keene, his truth is stranger than fiction. He's gone from football standout to drug dealer to undercover operative. And now, to screen star, with his story in development as a Hollywood film.

Still, says Keene, he thinks of the victims' families and hopes they'll find their answers. KEENE: That's all they can do is keep hoping. There was a glimmer of hope when Jimmy Keene was involved. Maybe something else will still evolve out of this. Maybe the things I've done and am still doing will still shine a light and give them hope at some point.